Medical and scientific practices
Medicine, during the 18th century took several dramatic turns. Early in the century, physicians still practice medicine that was reminiscent of past, classical practices. The Dutch physician Hermann Boerhaave (1668-1738), for example, based his medical decisions on ancient humor theory, combining them with more recent scientific discoveries. Other physicians, such as John Hunter (1728-1793) and Giovanni Morgagni (1682-1771) based their medicine on their own dissections and anatomical experimentation, resulting in a move away from ancient practices based on humor theory toward practices based on direct observation of the body’s systems. Theirs was a science grounded in philosophical and scientific empiricism inherited from Francis Bacon and applied to the body, its diseases, and their cures.
Medical scientists of the enlightenment, like scientists in other areas of scholarly activity, were hard at work finding relationships between and among natural phenomena. This effort led to a variety of taxonomies or classification schemas aimed at understanding systems involved in illness and health. Several notable contributors to this effort to develop nosologies of diseases were Erasmus Darwin (1731-1802), Francois Boissier de Sauvages (1706-1767), William Cullen, and Benjamin Rush.
Erasmus Darwin (1731-1802) an English physician and taxonomist who drew heavily from Linnaeus. Darwin’s system for classifying diseases was based on the following four types: (1) diseases of irritation, that arose from external sources (e.g., diabetes), (2) diseases of sensation, were caused by such factors as excess pain or pleasure (egs., vertigo, hearing loss), (3) diseases of volition caused by desire or aversion (e.g., tremor) and (4) diseases of association or contagion caused by problems in a related organ or system (egs. apoplexy, palsy).
Another figure who was highly influential in the creation of disease classification systems was the Frenchman Francois Boissier de Sauvages (1706-1767). In 1771, de Sauvages completed a three- volume taxonomy called Systematic nosology (Nosologie methodique) containing names and descriptions of 2400 diseases. The diseases, like those of Linnaeus, were divided into classes, orders and genera.
Included in the overall taxonomy were the following four genera related to speech disorders:
- Mutitas—organic articulatory disorders
- Aphonia—organic voice disorders
- Psellismus—disorders of rate and rhythm as well as functional articulatory disorders
- Paraphonia—disorders of vocal quality (Reiber & Wollock, 1977, p. 8).
Each of the above four groups were subdivided into subtypes. For example, the category of psellismus in de Sauvages’ system included the following eleven subtypes, several of which had to do with different kinds of sound errors (r, l, lisping, labials, gutterals), and another few with conditions that caused the articulation problem (metalic poisons, difficulty with movement of particular articulators, cleft lip and palate, tumor):
- Psellismus ischnophonia, difficulty of moving the velum, the uvula and the root of the tongue.
- Psellismus rhotacismus: problem with the r sound
- Psellismus lambdacismus: problem with l sound
- Psellismus traulotes: indistinctness, (lisping?)
- Psellismus balbuties: problem with labials
- Psellismus mogilalia: problem with labials (another kind?)
- Psellismus metallicus: an articulation problem caused by metallic poisons
- Psellismus iotacismus: problem with guttural sounds
- Psellismus nastas: nasality
- Psellismus lagostomatum: cleft lip and palate
- Psellismus a ranula: an articulation problem caused by tumors (Hunt, 1870, p. 41, Hunt 1882, p. 186 passim)
William Cullen (1775) borrowed from others’ classification systems, especially those of Linnaeus and de Sauvages when creating his own. Cullen also forwarded a theory of nervous energy which he saw as key to health. An excess or insufficiency of nervous tension caused all disease, according to Cullen. Too much tension was often characterized by a fever, to be treated by a depleting regiment including bleeding, a restricted diet, purging, and rest and sedation. A cold or chill, on the other hand, indicated too much relaxation and called for measures that enhanced nervous excitation such as stimulants, a heavy diet, or alcohol. Benjamin Rush, a well-known Philadelphian physician, studied with and drew from his teacher, William Cullen. Like Cullen, Rush attributed disease to either a weakened or excessive excitation of the nervous system.
This focus on nervous excitation was reminiscent of the ancient theory of vitalism or animal spirits. For the vitalist, both ancient and 18th century, life requires a force that is more than the material objects or inanimate processes in which it manifests itself. For there to be life, there must be a vital force present (Hergenhahn, 2001, p. 23). For the ancients, the force came from the gods. For Cullen and Rush, it came from a force, something like electricity.
For the most part, those in the medical establishment of the 18th century included in their category systems problems with speech, but not language. But there were two notable exceptions to this: Johann Gesner (1738-1801) a German medical writer and physician and Alexander Crichton (1763-1856), a physician from Scotland.
In 1770 Gesner described the symptoms of a patient, KD, who had what today would be called jargon aphasia. The patient’s problem, according to Gesner, was his inability to associate images with their verbal symbols. He called it verbal amnesia thereby distinguishing it from general cognition and from a problem with the articulators. Following in Gesner’s footsteps, Crichton published in 1778 a two-volume text on mental derangements. He included in those derangements disorders of aphasia, ranging from simple word-finding difficulties to a description of what today would be called Wernicke's aphasia. Both Gesner and Crichton drew heavily from association theory and empiricism of 18th century enlightenment as they worked to theorize about their aphasic cases.